Telephone switching apparatus and circuit



'Y (No Model.)

1 J. J. OGONNELL. v l

v TELE-PHONE SWITGHING APPARATUS AND CIRCUIT. No. 533.015.

Patented Jan. 22, '1895.

JOSEPH JOHN'OCONNELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE AMERI- y ,Y

CAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE SWITCHlNG APPARATUSv AND CIRCUIT.

SPECIFICATION forming vpart of Letters Patent No. 533,015, dated January 22, 1895.

Application tiled May 1, 1894. Serial No. 509,684. (No model.)

To a/ZZ whom, it may concern,.-

Be it known that I, JOSEPH JOHN yOCoN- NELL, residing at Chicago, 'in the county of Cook and State of Illinois, have invented certain 'Improvements lin Telephone Switching Apparatus and Circuits, of which the following is a specification.

This invention relates to telephone circuits and particularly to the interconnection of substation lines converging to one central station with the substation lines centering at other substations by means of multiple switchboards located at the said central stations which are connected together by trunk circuits.

In large cities the substation circuits are divided into groups each of which is provided with its own central station, and the said central stations are connected with each other by trunk circuits. Owing to the increased utilization of telephonie service, and the con'- sequent increase of the trunking between the central stations, itis becoming more and more essential that the trunk conductors, whereby one substation is connected to another, shall beso arranged and Iitted that not only shall the connections be completed in the quickest possible time, but also, that when conversation is iinished between two connected substations their lines shall be disconnected as promptly as possible, in order that they may be ina condition to be utilized by the other substations, and so that the best service may be given to all of the substations.

To this end my invention consists in a combination of apparatusat each central station associated with the multiple switchboards there, comprising trunk` and order circuits and switching and signal apparatus, by means of which first, the ordinary operations of answering a call from a substation and looping or linking the same to a substation at another or distant switchboard will automatically notify all the operators to whose tables or sections the trunk circuit used is multipled or extended that the said trunk is in use or busy; second, at the same time the trunking operator at the distant switchboard will be notitied that a connection is wanted by a particular trunk terminating there; third, when a connection is made by the trunking operator from the trunk terminal to the substation line called for, an indication of the fact is made at the table ot the receiving or tirst operator; fourth, when the conversation is concluded and the clearing out annunciator so indicates at the receiving board, and the connections are then taken. down, there, the trucking operator is automatically notified thereof, and, tifth,when the trunking operator disconnects the trunk terminal from the called substation line and said trunk is not in use, an indication of the fact is made at all the switchboard sections, at the receiving central station to which the saidrtrunk terminal is multipled, and the circuits are returned to the normal condition, all of which I will now proceed to describe and claim.

The drawing which illustrates the invention shows the circuits and apparatus at the table of a receiving switch-board operator, and at the table of a trunking board operator each located lat separate telephone central stations with an order and a trunk circuit extending between them, all in their normal or quiescent condition of which the following is a description: a

At the receiving board L represents a substation circuit and J4 the open terminal answering spring jack therefor.

P is the answering plug and P2 the connecting plug of a looping or linking pair.

I is an induction coil.

'Tis the operators telephone transmitter and t the receiving telephone.

K is the principal switch or key by means of which the operators telephones are switched into the plug cords and the several operations are superv-ised, as is particularly set forth in Patent No. 430,747, granted to me June 24, 1890. It consists ot' the wedge or plunger w and the several springs 4, 5, 6, 7, 8, 9 and 10 and contacts 11,12, 13, 14 and l5.y The spring 4 is connected with the wire t' and to the tip of the plug P?, the spring 5 being connected to the tip of the plug P, and the spring lO is connected by conductors g and g2-to the sleeves of the plugs P and P2 respectively. Springs G and 7 are connected by wires Z and lo to the secondary of induction coil I and to operators telphone receiver t, a condenser c8 being connected to prevent passage of straight IOO battery currents. A clearing out annunciator m is bridged in between the spring and contact 11, and by means of spring 4 between plug cord conductors g and t'. A five hundred ohm resistance is placed in a ground branch 'n from the wire Z, and a condenser c2 is placed in a wire p from the spring o to the branch n. The contact is connected by w`ire 38 to test battery B2 and to ground by wire 44. A branch wire 37 extends from wire 90 to Wire 38 and includes a five hundred ohm resistance coil. The contact 12 is connected by wire 18 to contact 2O of key k2 and includes a signal s2 to indicate the reception of a generator current at a distant station, and spring 8 of key Kis connected by wire 35 with spring 16 of key k2, the spring 17 being connected by wire 34 with contact 26 of key 7a4 and from thence by wire 42 to ground through the generator G. The Wire'p is connected by wire 36 to contact 22 of key 7t2,its opposite contact 23 being connected by wire O to conductor 7c. Spring 25 of key 7c3 is connected by Wire 33 with contact 28 of key 7a4 and spring 24 by wire 32 to contact 27. Spring 31 of key 7a4 is connected by conductor 39 to the tip of order circuit plug P3 and the spring by the other conductor 40 to the sleeve of the said plug.

A is an order trunkthe conductors of which a b are respectively connected to the springs 56 and 55 of the springjack .T on the receiving board, and to the springs`57 'and 58 ofthe jack JL on the trunking board.

V.l2 is a four pointed contact spring jack forming the terminal of an out trunk C from the receiving board to the trunking board; the conductor e thereof extending from the spring 50 to spring 76 of key switch K2 and 62 to the spring 8l of the key K2.

the conductor f extending from, the spring 52 to the sleeve of trunk plug P5 with a branch Test ring 49 is connected by wire 54 to the spring 52. Springs 5l and 53 are in contact with the inner surface of the springs 50 and 52 and the former extends to ground by wire 44 through the battery B2 and the latter goes to ground by wire 47 through the helices of relay R. The armature r of relay R is adapted to mechanically close a local circuit 48 when its spring pulls it to press against its back contact u, and causes the busy signals to be displayed, the helices of which are then energized by the battery B2.

At the trunking board, K2 is the principal switch or key by means of which the operator conducts the operations there. Its spring 75 is connected by wire 60 with the tip of plug P5. Spring 77 is grounded by wire 63 which includes a resistance of tive hundred ohms. Spring 78 is grounded through the order signal s3 and battery B5 by wire 74. The contact 84 is grounded through generator G2 by wire 65, and contact 85 is grounded th rough disconnecting signal s4 by Wire 67. P4 is the connecting plug of the order circuit B, the tip and sleeve of which are connected by conductors c and d with one side 73 ot' the repeating coil l2, the other side of said coil 66 being connected by wires 68 and 70` to one side 69 of repeating coil 12 including the operators telephone t2 with a branch 8l to ground. The primary 64 of coil 12 includes transmitting telephone T2 and battery B". A branch wire 71 connects between the sides 66 and 69 of coils 12 and 12 and extends to the Wire 72, which wire connects contact 82 with ground and includes test battery B6.

A grounded branch 59connects with conductor d of circuit B, and includes a onethousand ohm call bell F by means of which the receiving operator may signal the trunking board. L2 indicates the conductors of a substation and J5 `the springjack therefor upon the section of the multiple board represented.

As before stated, the circuits are represented in their normal condition. At the receiving board the key switch K is Withdrawn, the loop plugs P and P2 are disconnected, the plug P3 is inserted in the order trunk A, and the signals s2 and s are not displayed. At the trunking board the wedge to2 of key switch K2 is pushed in so that the springs 75 and 77 and springs 78 and 81 are respectively brought into contact, `the signal s4 being in an open branch by reason of the separation of its contact 85 from the spring 75; the signal S2 not being displayed as an order signal as there is a circuit from ground by wire 74, battery B5, signal s3, wire 74, springs 78and 8l, Wire 62, conductorf, springs 52 and 53, wire 47, relay R attracting the armature r and opening the local circuit 48, andwires 47 and 44 to ground. At the receiving board the signal s2 is not displayed as it is on an open grounded circuit, and the signal s is not displayed because its circuit 48 is opened by the armature 'r as just described.

The operation is as follows: Acall comes in on circuit L from a substation and the line annunciator H indicates `thet'act to the operator at the receiving board, who pushes in the wedge w of switch key K until its part 2 forces the springs 6 and 4 and 7 and 10 together, which act connects the telephones T andtin circuit with the plugsP and P2 through their cord conductors. The answering plug P is inserted into the terminals of the answering jack J4, thus completing the circuit between the substation and the operator in a manner well understood. The number of the substation Wanted having been ascertained to be at another or distant multiple switchboard a test is made to see if the connecting out-trunk circuit C is busy at any other section of the switchboard or not. This is done by touching the tip of plug P2 to the ring 49 of the springjack J2. At the saine timethe wedge w of key K is forced inward until the spring 10 comes in contact with the contact pin 15 thus establishing a circuit from plug P2, conductor t', springs 4 and 6, wire Z, through the telephone t, wire 7c, springs 7 and l0, contact 15, wire 38, and test battery B4 to ground.

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The trunk'not being engaged the plug P2 is inserted into the jack J2. The plug tipraises the spring 50 to rest thereonseparating it from the spring 51, and the springv52 is raised to rest upon the plug sleeve and is separated from the spring' 53, and the conductor c' is connected to conductor e and the conductor g2 with the conductorf of the trunk C. The effect of the insertion of the plug P2 into jack J2 is to cause all the busy or'line-in-use sig# nals s to be displayed at the several sections of the switchboard as the circuit from ground by wire 74, including battery B5, springs 78 and 8l, wire 627conductorf, springs 52 and 53,

wire 47, including relay R, to ground, is broken by the separation of the springs 52 and 53. Consequently the springof armature fr' closes l the local circuit 48 by pressing the same to its back contact u, bringing the battery B2 into operation and energizing the helices of the signals. At the same time the ordersignal s2 at the trunking board is displayed to indicate to the operator there thata connection is desired from trunk circuit C; and the signal s2 is displayed because a circuit is made from ground um wires 46, and k, springs 7 and 10, wire 90, condnctorg2, sleeve of plug P2, spring 52 of jack J2, conductorf, wire 62, springs 8l and 78, wire 74, helices of order signal s2, and battery B5 to ground. The receiving operator gives the order to the trunking board operator over the order circuit A by pressing the key 7a2 and forcing the springs 25 and 24 against their respective contacts 22 and 23 which loops the order circuit A to the receiving operators telephones as will be seen by tracing from repeating coil l2 by conductor d, sleeve of plug P4, spring 58 of jackJ4, conductor b, spring 55 of `jack J, sleeve of plug P2, conductor 40, spring 30, wire 33, spring 25, wire 36, condenser c2, wires n and Z, telephone t, wires and O, spring 24,'wire 32, spring 31, conductor 39, tip of plug P2, spring 56 of jack J, conductor a, spring 57 of jack J4, tip of plug P4 and conductor c to coil I2. After the trunking operator has received the order, the line called for is tested by touching the tip of the trunk plug P5 to the test ring of the called jack J 5 in the usual manner, and finding the line disengaged inserts the plug into the jack and pressing in the wedge cu2 of the key K so that the spring 75 touches the contact 84, rings the substation, a circuit being .formed from ground va, generator G2, wire' 65, spring 75, wireh60,and by tip of plug P5 to the line L2. After ringing, the wedge to2 is drawn out. This movement removes the operators telephones from the circuit, and leaves the two substations connected together through the trunk circuit C and looping plugs P2 and P; and legs to the circuit the disconnection signal s4 at the trunking board, and resets the O. K. or all right Signal s2 at the receiving operators board to give notice there that the connection had been made with the called for line, and also resets the order signal s2. The circuits from jacks l J4 to Jare traced'as follows: from tip of plug P, conductor h, springs 5 and 4, conductor ,tip of plug P2, spring 50 of jack J2, conductor e, springs 76 and 75, conductor 60 to tip of plug P5, returning by sleeve of plug P5, conductor f, spring 52 of jack J2, sleeve of plug P2, conductors g2 and g, to sleeve of plug P. The disconnecting signal s4 is legged to the spring 75 and so to the conductor 60 when the wedge 2v2 is pushed inward by the contact 84 coming ,into contact with the said spring. The O. K.

signal s2 and the order signal s2 are reset by the opening of the circuit in which they are included by the separation of the springs 78 and 81. When the conversation is concluded, either substation rings off which causes the clearing out annunciator m to display its shutter, whereupon the receiving operator withdraws the plugs P and P2 from their jacks J4 and J2. This act closes the springs 50 and 5l, and springs 52 and 53 respectively of the jack J2, thus making a circuit from ground/via wire 44,' springs lgand 50, conductor e, springs 76 and 75 contact 85', wire 67, through disconnecting signal s4 to ground, and sets ordis-v plays the said signal to notify the trunking operator that the lines are disconnected at the receiving board, and of the duty of disconnecting the trunk from the substation line. The operator then pushes in the Wedge w2 of key K2, which act resets the signal s4 by sepa-` rating the spring 75 from the contact 85 and also closes the circuit of the battery B5 at the springs 78 and 8l, and at the same time resets the busy signals s at all the receiving boards, to indicate that the trunk C is not busy, this being accomplished by the attraction of the relay armature fr by its helices and the opening of the local circuit 48, as previously described. l

The receiving operator can tell at a glance if the connection at the trunk board has not been taken down as the busy signals will not disappear until the trunk operator has attended to this duty, and the chances that the trunk circuit and the substation line will be heid up are greatly reduced.

I claim- 1. In a trunking system between two central stations a trunk circuit extending Abetween each station provided with switching and looping apparatus at the receiving and trunking terminals thereof; and signals at the receiving terminal normally indicating that the circuit is not in use, and an order signal at the trunking terminal normally not displayed the said signals being controlled by a source of electricity at the trunking terminal; whereby upon looping a substation line to the trunk terminal at the receiving switchboard, the signals there are changed to indicate that the trunk circuit is busy, and at the same time the order signal is displayed vat the trunking switchboard.

2. In a trunking system between vtwo. switchboards a trunk circuit extending between each station provided with switching IOO IIO

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and looping apparatus at the receiving and trunking terminals thereof, and a signal at the receiving board operated by a` source of electricity at the trunking board to indicate that the called substation line has been connected to the trunk circuit; switching devices at the receiving board whereby the circuit of said signal is closed and the signal itself set or displayed by the connection ot the looping apparatus to the trunk terminal at said receiving board; and switching apparatus at the trunking board whereby the circuit of said signal is opened and the signal reset when the looping apparatus at said trunking board is connected to the called line, substantially as described.

3. In a trunking system between two central stations, a trunk circuit extending between each station provided with switching and looping apparatus at the receiving and trunking terminals thereof, and a disconnecting signal at the trunking terminal; means whereby said signal is legged to one s ide of the talking circuit when the trucking operator connects the trunk circuit with the called line; and means whereby upon the disconnction of the looping apparatus at the receiving board the circuit of said signal is completed through asource of current at the receiving, board, substantially as described.

4. In a trunking system between two central stations a trunk circuit extending between each. station provided with switching and looping apparatus at the receiving and trunking terminals thereof, and a disconnecting signal at the trunking `terminal operated by a source of electricity at the receiving terminal, and busy signals at the receiving board operated by a source of electricity at the trunking board, whereby upon the Withdrawal of the looping apparatus from the trunk circuit terminal at the receiving board, the disconnecting signal will be displayed and the busy signals will be reset to indicate line not in use.

In testimony whereof I have signed my `name to this specification, in the presence of two subscribing witnesses, this 25th day of April, 1894:.

JOSEPH JOI-IN OCONNELL.

W'itnesses:

ALFRED A. THOMAS,

A. B. RAYMOND. 

